Have the doctor check for vaso-vagal syncope. That runs in my family and has caused the symptoms that you describe for each and every one of my brothers and sisters at some point in time, including me. One of my sisters even ha a pacemaker installed because of it.

In the meantime, let him know to sit down anytime he starts to get that lightheaded feeling. I have passed out from it, and I have the scar on my head to prove it. It's much safer if he sits down until the feeling passes.

That's just one of many causes that it could be, but it's worth looking into.

These symptoms could also be caused by a fast drop in blood pressure. Does your friend take any kind of medications? Certain medications can cause dizziness or even cause your blood pressure to drop rapidly. As mentioned above it could have been a vagal response as well which also can cause a rapid drop in blood pressure.

Another option to look at may have been an episode of SVT or supraventricular tachycardia. This happens when an electrical impulse comes from the wrong area of the heart and causes your heart rate to increase suddenly. Your pulse will usually just jump up to at least 150 and sometimes much higher. This can cause the light headedness, dizziness, feeling like you're going to pass out, and you can feel your heart pounding.

Though I've been to the ER a few times with this your pulse will usually come down on it's own as mine did. Sometimes it may only last just a minute or two. If it does last longer and fails to come down by itself there are medications they can give at the hospital. If medications don't work to bring the pulse rate down they can also try cardioversion which is sending an electrical shock to the heart to essentially reset it.

Unless SVT occurs very often there isn't usually anything they do for it other than medications to help control your pulse and keep it beating at a normal rate. These episodes can come on without any warning and sometimes without any trigger. If it begins happening all the time to your friend and his pulse does not return to normal on it's own there is a procedure called an ablasion that basically kills the area of the heart where the faulty electrical impulse is coming from.

If it is SVT there is not a whole lot he can do except have the symptoms treated when it arises. It's scary I know. Anxiety also presents itself much like that. I know he may not have been feeling anxious when the symptoms first came on but it could still have been a bout of anxiety.

Anxiety attacks can come on without any warning as well. They often make you have palpitations, short of breath at times, and can make you feel light headed and dizzy. It's really crazy what a bad bout of anxiety can do. You literally feel like you may be dying sometimes. If he contninues to have these episodes this may be another thing to look at. They can prescribe some as needed medication to help keep the anxiety at bay. Medications like Xanax are fairly quick acting and can be taken when the symptoms come on.

I certainly hope your friend continues to feel better. Hopefully he will have no more problems and this was a one time fluke episode. Best wishes to you both!